added get function to std.json.Value

[curuvar]

Added a get function to easily get a specific item from a Value ObjectMap.

For example, given the following JSON:

{
  "a": [1, {"x": 2, "y": 3}, 4],
  "b": "something else"
}

Calling get(i64, &.{"a", "1", "y"}) will return 3, and get([]const u8, &.{"b"}) will return "something else".

Valid types are i64, f64, []const u8, bool, std.json.Value, std.json.Array, and std.json.ObjectMap.

Returns null if the key path cannot be found and error.WrongType if the data in the value
is incompatible with the requested type.

[linusg]

This API looks extremely awkward, if anything something more widely useful like JSONPath (RFC 9535) should be implemented.

[curuvar]

I personally don't think just passing a array of selectors is too awkward, but I can see how passing in a simple string might be easier.

I'll look into allowing something like get( u64, "some.path.4" )

[linusg]

I think you should present a motivating use case before putting more work into this.

[curuvar]

Let me think more on that. I may resubmit later.